Are plants sentient? How much we don’t know about the world’s flora.
Our perceptions form the basis of our views on nature and our place in the world. When we are young, we are almost all interested in animals. But very few children are so drawn to plants. This is not surprising, as animals possess far more in common with us so we are able to relate to them.
But is this bias affecting the way we look at plants and trees? Do we have to find new ways of looking?
We live in a period of ever-changing perception. In the last 50 years alone, we have seen for the first time in human history the deepest ocean abyss and the dark side of the moon, as well as regular viewings of our home planet from space. Our perceptions are augmented by technology, and our possibilities expanded as a result.
But despite this, we are still living in the dark ages when it comes to understanding the basics of 99% of the world’s organic material. Plants and trees make up all but 1% of the earth’s biomass. Yet our understanding of them is inadequate at a time when most scientists insist our industry is contributing to climate change, and that we have, through our actions, instigated the sixth great extinction event in earth’s history.
Currently, we have a rough tally of 20,000 species of plant on the planet, although this could be wildly under the true figure: it has been suggested that we know only between 5 and 50% of extant plant species, leaving vast numbers of species yet to be discovered. It is a sad fact to think that many of these will become extinct before science gets a chance to understand them – and in an age of oncoming antibiotic resistant bacteria, it is short sighted in the extreme to lose such potentially vast resources for medicine.
And the age-old questions about plants persist still. How do they sense things? What controls their behaviour? They don’t appear to have a nervous system at all, yet they release chemicals to fight off attackers and communicate with each other, they move toward sunlight, and they have been observed to ‘recognise their own kin’ as they behave differently to these plants than others of the same species.
Our lack of understanding comes from how radically different we are to them. I personally would not describe them in any way as sentient, but like all living things they do respond to certain stimuli. With over 20 different senses, plants can detect obstacles in front of roots (before reaching them), sense gravity, and can even hear: plants have been seen to respond to recordings of caterpillars munching on leaves.
There is also recent research that plants may have the ability to learn. Experimenting on a Mimosa plant, which collapses its leaves to ‘play dead’ to any herbivore predator, the animal biologist Monica Gagliano repeated the stimuli without damaging the leaves. After five or six drops, she stated, the plant stops collapsing its leaves, as if it knows that the stimuli is not threatening. What is more, it apparently recalled that for a month long period.
But how can this be possible if they don’t possess a nervous system and a brain? Darwin believed that the plant’s ‘brain’ was located in its root tip. This has been backed up somewhat by work from Stefano Mancuso, who believes that a single plant to better being viewed as a combination of organisms working together – which would explain why such an organism can survive with 90% of its mass being destroyed or eaten. With each plant possessing millions of individual root tips, it is this combination of networks that act as the information-processing centre of the plant.
One thing is absolutely for certain though. There is so much we don’t know about these organisms that dominate life on earth, and if the above information isn’t enough to inspire some curiosity within us, then I give up hope.
So next time you are watering that rose or orchid, just think, it probably knows you are there.